1. Technical Field
This device relates to friction welding apparatus that rely on friction between two mechanical components. One of the components develops friction at the interface of the two parts to be joined in order to generate the required temperature for welding. The other component produces pressure after the required temperature is achieved completing the weld. Currently, there are two general methods for friction welding as disclosed by the American Welding Society "Inertia and Continuous drive". Both methods employ high velocity and pressure to achieve the friction required to weld. "Inertia" method stores total energy in a fly wheel that becomes free wheeling at one point in the weld using stored energy to complete the weld. "Continuous Drive" method provides a motor and clutch brake wherein an element is brought up to speed and the clutch is engaged with moderate interface pressure generating heat. A brake is applied once the forging range of material is reached.
2. Description of Prior Art
Prior art devices of this type have relied on a number of different friction welding techniques utilizing the "Continuous drive" and "Inertia" methods and varieties on same, see for example U.S. Pat. Nos. 3,542,274, 3,542,275, 3,562,073 and 3,750,927.
In U.S. Pat. No. 3,542,274 a speed program friction weld control is disclosed wherein an electronic loop employing circuits to continuously compare critical speed of the drive with the program speed throughout the weld cycle and adjusting same.
U.S. Pat. No. 3,542,275 discloses a reciprocating friction welder that provides means to position and align weld pieces in a reciprocating friction welder.
U.S. Pat. No. 3,562,073 is directed towards friction welding a pair of plastic members in an angular relationship in a spin welding device to weld an elbow fitting to a pump housing.
In U.S. Pat. No. 3,750,927 a device for angular alignment of inertia/friction weld parts wherein weld parts are aligned by turning one part with respect to the other through the hot plasticized interference after the parts have been welded.
U.S. Pat. No. 4,552,609 is directed to a method and application for friction welding having a controlled system that terminates the applied rotational force after determined rotations have been achieved allowing the rotating element to coast, and a final forging pressure is applied.
Applicant's method of the invention uses a pressure alignment of parts to be welded before rotation i.e. welding takes place. Accordingly, it is the applied torque between the parts that achieves welding thereof within a fraction of a second by rapidly accelerating to full speed and de-accelerating to a predetermined stop position before the weld sets, all within several arc seconds.